Lee de foeest



N0 MODEL.

No. 749,372. PATENTED JAN. 12, 1904.

L. DE FOREST.

ART OF WIRELESS TELEGRAPHY.

APPLICATION FILED JUNE 4, 1903.

Fig. 1.

A Fig.2

U '1 X 1412 Fig.4. T2 0 j U2 WITNESSES: //v VENTOH Z ATTORNEY UNITEDSTATES Patented January 12, 1904.

PATENT OFFICE.

ART OF WIRELESS TELEGRAPHY.

SPECIFICATION forming part of ,Letters Patent No. 749,372, dated January12, 1904. Application filed June 4, 1903- Serial No. 160,028. (Nomodel.)

To all whom it pea/y concern:

Be it known that I, LEE DE Fonns'r, a citizen of the United States, anda resident of the city, county, and State of New York, have inventedcertain new and useful Improvements in the Art of Wireless Signaling, ofwhich the following is a specification.

My invention relates to an improvement in the method of transmitting andreceiving signals by means of electric radiations which are transmittedaerially or without wires.

My invention is particularly designed for use in conveyingwarning-signals in such places and under such circumstances as a sirenor foghorn isnow used, although it-will be evident that it may beemployed for many other pu 1'- poses than this.

One object of my invention is to provide a method of Wireless signalingof such simplicity and reliability that it may be used by any one ofordinary intelligence without any special preliminary training.

The purpose and scope of my invention will appear from an inspection ofthe following specification and the claims terminating the same.

In the drawings accompanying herewith I have shown forms of apparatuswhich may be employed in carrying out my invention, the same being thosenow preferred by me.

Figure 1 diagrammatically shows an apparatus designed for radiatingsignals in accordance with my invention. Fig. 2 shows a sendingapparatus employing an induction-coil and a VVehnelt interrupter. Fig. 3shows a sending apparatus employing an induction-coil and an interrupterof the hammer type, and Fig. 4 is a diagrammatic illustration ofapparatus for receiving such signals.

If an apparatus for receiving signals sent by aerial electric waves beprovided with a wave-responsive device which is automatic orself-restoring and capable of sufficiently rapid changes in itscondition and if with such a device'a telephone-receiver. or otheraudible translating or indicating device be employed, the emission of acontinuous series of waves by the transmitter will produce a continuoussound in the receiver, the tone of such sound being determined by thefrequency of the tone, as well as the order of succession of the changesand their intermittcnce, may be employed to transmit signals. Any otherform of receiver which will indicate variations in spark frequencies maybe employed as a substitute for the telephone-receiver. I prefer,however, to employ the telephone-receiver, as it is a reliable andsimple instrument with which most persons are'familiar.

The above-stated result will follow whatever the means by which thespark frequency is changed. I have, however, found that when analternating-current source of electromotive force as a generator isemployed the spark frequency may be sufiiciently varied for this purposeby varying the distance between the sparking terminals. This, it isevident, may be carried out by a numerous variety of mechanisms.

In carrying out my present invention 1 employ a radiating conductor ofany suitable type and means for impressing thereon oscillatory impulsesof a high frequency and at the sametime varying the frequency of re.

currence of the sparks producing such oscillatory impulses in anydesired manner, thereby creating in a suitable receiving instrument atone which rises and falls in accordance with the variations produced inthe frequency of the exciting-sparks. At the same time I may wheneverdesired break the continuity of the spark, thus further individualizingand differentiating the signals.

Referring to Fig. 1, which illustrates a sending apparatus employing analternating generator, A represents the radiating antenna, to which isconnected one of the terminals of the spark-gap S, the other terminalbeing eonnectedwith a ground E. The oscillatory impulses are hereinshown as produced by means of an alternating generator G, which isconnected with the primary T of a transformer, the secondary T of saidtransformer being in the oscillating system, which is connected with thetwo terminals of the spark-gap, said system also preferably containing acondenser K, connected across the terminals of the sparkgap. This methodof producing the desired oscillations is illustrated merely as a commonand convenient method. Any method or apparatus for producing suchoscillations may, however, be substituted therefor.

The terminals of the spark-gap S are so .mounted that they may haverelative movement toward and from each other. Any method of mountingwhich secures this result may be employed. 1 have shown this result asbeing secured by mounting one of the spark-terminals upon a lever F,which is pivoted upon an adjustable pivot J. This pivotpoint may be andis herein shown as adjustable both in elevation and in distance from thespark-gap, so that the amount of movement of this terminal as well asthe location of the path of its movement relative to the other terminalmay be adjusted. The method herein shown for securing such adjustmentsconsists in providing both the lever F and a standard 1, upon which itis pivoted, with a horizontal slot 1, adapted to receive a clampingpivot-bolt J, and also by carrying the standard A in a base L, withinwhich it may be vertically adjusted and held in position by aclamping-bolt L. The lever F carries a roller f upon the end oppositethe spark-terminal, said roller being held in engagement with a cam M bymeans of a spring H or other suitable device. The cam M is herein shownas being a disk having a series of projections thereon adapted to raisethe roller f and hold it raised for a short time. These elevations maybe varied in height, in extent, and in separation and also may be madeto succeed each other in various orders, thereby .rect-current source ofelectromotive force may, however, be employed to carry out my invention.Devices designed to use such a source of electromotive force are shownin Figs. 2 and 3. The device shown in Fig. 2

' V employs an induction-coil C, a source of ditaining an acidelectrolyte and a platinum point 2, which passes through a gland orstuffing-box in the side of the jar and projects a variable amount intothe electrolyte. The spark frequency with this device depends upon thearea of surface of this platinum point or rod which is exposed. This rodor an extension thereof extends outward of the jar and is held againstthe surface of cam M by a spring 3. As the cam revolves the rod 2 isforced inward and outward alternately under the action of the cam andthe spring, thus varying the exposed surface of rod 2, and therebychanging the frequency of the sparks produced. In Fig. 3 aninduction-coil device employing an interrupter of the hammer. type isshown. This has an armature mounted upon a spring-arm O and attracted bythe core of the induction-coil, one side of the battery B beingconnected through the coil C with the spring-arm O and the other with acontact-pin X, with which the springarm normally makes a contact, whichis broken by the attraction of the coil when current passestherethrough. One element determining the period of such an interrupteris the free length of the arm 0. I have shown a block U embracing thisarm and movable lengthwise thereof to vary its period. This block iscarried by a rod U, which is mounted to slide in suitable guides and atone end bears upon a cam M, upon which it is held by a spring U. Thiscam may be turned by any suitable means, those shown being such as havebeen hereinbefore described. Numerous other mechanisms maybe employed tosecure the same result. Those described have been given only as examplesof simple and desirable forms of devices for use in carrying out myinvention.

It is evident that with any of the forms shown the cam may be made tobreak the en ergizin'g-current to the spark-gap, if desired, so as tocombine breaks in the sound with the variations in tone, thus enabling agreater variation in signals to be obtained. The receiving apparatusemployed for such a'message may be any form of wireless-telegraphreceiver which is self-restoring or automatic in its action, combinedwith an indicating instrument which produces an audible sound or othermanifestation which varies in accordance with the variations in thespark frequencies. In Fig. II have illustrated a simple form ofapparatus which may be employed. This consists of a collecting conductoror antenna A, a wave-responsive device R, connected in series in saidantenna and the earth E, and a local circuit which contains a battery Band a telephone V, the same being connected on opposite sides of thewave-responsive device, so as to include the same therein.

In using my method for conveying warningsignals it is designed that asending apparatus shall be placed. at the point from which it is desiredto send the signals. This point may for purpose of illustration beassumed to be a location upon a shore from which it is desired to warnapproaching vessels of their proximity thereto. In such case when theshore is not visible, so that warning may be conveyed in that way, mymethod would be employed and the sending apparatus being put in actionwould emit a constant series of waves produced by sparks which vary intheir frequency in accordance with a prearranged e plan. In order that avessel may avail itself 1 i of this warning, it is necessary that itshould be equipped with a wireless receiving apparatus of the characterherein indicated, in which case as soon as it came within the field ofthe waves radiating from the sending-an- I tenna its receiver would emita sound which would rise and fall in tone in correspondence with thecharacter of the waves emitted. The variations characteristic of thevarious stations being known by means of a chart or table, the 2 personreceivingsuch signals aboard the vessel would know of his proximity to aparticularstation and would thus be warned of approach to shore in caseswhere other means would fail. The use of my method of signal- 5 ing is,however, not confined to communicating signals from shore to vessel, butmay be employed to give warning of the approach of two vessels towardeach other. By use of a y code previously arranged such signals may 3*be made to indicate the course which each i vessel is pursuing, andwill thus tend to pre vent collision. It is possible to quickly change ifrom one signal to another, as by changing I cams. In a similar way byusing a code my 1 method may be employed for the transmission ofnumerous messages.

IVhile I have heretofore described the emission of the waves as beingcontinuous, it is evident that they may be emitted for a certain periodof time and then intermitted for a certain period of time, therebyfurther increasing the means by which different stations may beindicated and also preventing the signal sent out by onevessel frominterfering at all times with the signal sent out by another vessel.This method of operation may also be used to indicate thebeginning andending of a complete signal. When so operated, the action 5 of thedevice would be still more analogous to the method of operation of awhistle or foghorn as a warning. The receiving apparatus for use incarrying 1 out my invention may be made very simple and reliable, sothat, any one of ordinary intelligence may keep it in good condition. Noknowledge of a telegraphic codeor special ability, such as is requiredfor using such a code, is needed. Any one with a chart before him mayidentify the signal sent in the same way as mariners identify thevarious lights by their color and time of exposure.

Having thus described my invention, what I claim, and desire to secureby Letters Patent, 1s

1. The method of wireless signaling which consists in radiating acontinuous series of high frequency, electrical waves having a sparkfrequency varied in a predetermined cycle and in therewith producing atthe receiving-stations manifestations which vary in accordance with thevariations in spark frequency.

2. The method of wireless signaling which consists in radiating acontinuous series of high frequency, electrical waves having a sparkfrequency varied in a predetermined cycle'and in therewith producingsounds which vary in pitch or tone in accordance with the variations inspark frequency.

3. The method of wireless signaling which consists in radiatinghigh-frequency, electrical waves varied in their mechanical frequency in-a predetermined cycle and in therewith proa predetermined and recurringcycle and in therewith producing manifestations at the receiving-stationvarying in the same cycle.

5. The method of communicating a warning-signal which consists inemitting a recurring series of high-frequency electrical Waves varyingboth in their spark frequencies and in their continuity in accordancewith a predetermined cycle, and in translating said waves into audiblesounds.

6. The method of communicating a warning-signal which consists inemitting a recurring series of high-frequency electrical waves varyingboth in their spark frequencies and in their continuity in accordancewith a predetermined cyele, and in producing thereby manifestationswhich vary in accordance with the variations in said waves.

In testimony whereof I have hereunto affiXed my signature, this 16th dayof May, A. 1). 1903, in the presenceof two witnesses.

LEE DE FOREST.

itnesses:

P. A. HALL, H. L. REYNOLDS.

